Melt the butter in a large heavy-bottomed pot over medium-high heat. Add the flour, stirring to combine, and cook for 2 minutes until light golden. Slowly pour in the milk and cream, whisking as you pour. Bring the liquid to a simmer, stirring the whole time. Simmer until the sauce is thick enough to cover the back of a wooden spoon. Add the nutmeg, cayenne, egg yolks, cream cheese, Monterey Jack cheese and chives. Season to taste with salt and pepper. Stir until combined and the mixture is smooth. Fold in the crab meat. Pour the mixture into a buttered casserole dish. Crumble the crackers on top and dot with a few pieces of butter.

Place in the oven to bake for 15 minutes. Place under the broiler until golden-brown. Serve the dip warm with more buttery crackers.

Tips - Be careful to gently fold in the crab so the meat doesn't break up. - Stir in cooked pasta shells and bake for a creamy crab mac 'n' cheese!